1. Field of the Invention
The present invention relates to a method for detecting a running internal combustion engine in a combustion engine as the first drive unit and a second drive unit make a contribution toward driving the hybrid vehicle and a device for performing the method.
2. Description of the Related Art
Vehicles having a hybrid drive structure have an internal combustion engine and usually an electric motor as the second drive unit. The drive torque during driving operation of the hybrid vehicle may therefore be applied by both drive units.
If errors occur in the internal combustion engine, they are manifested by misfiring on the cylinders of the internal combustion engine.
Constant misfiring on all the cylinders of the internal combustion engine is not noticed further in a hybrid vehicle because the second drive unit continues to ensure the driving operation of the hybrid vehicle. Constant misfiring on all cylinders is not detected by known irregular running methods because the irregular running is optimal. The segment time of all cylinders is of the same length.
Published German patent application document DE 10 2006 012 868 A1 describes a method for diagnosing misfiring of an internal combustion engine which is situated together with an electric motor in a hybrid vehicle. The signals of the control of the internal combustion engine are coupled with the signals of the electric motor, so that a diagnosis of the internal combustion engine with regard to the occurrence of combustion misfiring may be performed with the aid of a vibration analysis using these signals.